Method of producing di-methyl-pyrazolonyl-diphenyl



Patented Aug. 13, 1935 UNITED STATES METHOD CF PRODUCING DI-LIETHYL-PYBAZOLONYL-DIPHENYL Iwan I. Ostromislensky, to Medico Chemical NewYork, N. Y.

New York, N. Y., asslgnor Corporation of America,-

No Drawing. Application July 16, 1934, Serial No. 735,425 I 2 Claims.

My invention relates to methods of producingi-methylpyrazolonyl-diphenyl and its derivaves. 1

As-I disclosed in my patent applications, Serial 5 Nos. 717,723 filedMar. 28, 1934, and 733,870, filed with 2 mol. of ethylacetoacetate.

Diphenyldihydrazine, required for this reaction, could be obtained byArheidts method, by reducingdiazotized benzidine with sodium sulfite ortin chloride (SnClz) The yield of the preparation produced by thismethod is, however, quite insignificant. I developed, therefore, a newand more eflicient method of producing diphenyldihydrazine fromdiazotized benzidine by sodium hydrosulfite (NazSzOO as a reductionagent.

Condensation of diphenyldihydrazine with ethylacetoacetate passessmoothly when the mix- ;ure is heated on a boiling water bath for a fewours.

Example I (a). Preparation of diphenuldihydraeine A. thoroughlyhomogenized mixture oi! 74.4 grams of benzidine (free base) with 200grams oi ice and 220 grams of hydrochloric acid of spec. gr. 1.19, isdiazotized, using potassium iodide starch paper for control, by thesolution of grams of sodium nitrite in cc. of water. The process ofdiazotizat-ion must be conducted in a vessel of a comparatively largecapacity as the mixture has a tendency to form a foam.

To the resulting solution of diazo-compound isoddodatflrstwoaotconcentratedhydrochloric acid, and immediatelyafterward a previously cooled solution or 200 grams of sodiumhydrosulflte in 1000 cc. of water containing about 20 drops of 40%sodium hydroxide. Concentrated hydrochloric acid is added to theresulting mixture, this time 400 cc. The mixture is well stirred andheated on a direct fire at boilin temperature for one half hour. Thereddish-brown color of themixture then turns into pale-yellow color of asandy hue. The settling amorphous precipitate is filtered on theBuechner funnel and washed with water for removing mineral admixtures.

The product represents di-hydrochloride of diphenyldihydrazine,containing, however, other substances as admixtures; When heated in acapillary, the substance melts and decomposes at about 260 C. In orderto obtain a free base, the substance is dissolved in a large amount ofboiling water, filtering, saturated solution of sodium acetate is addedin a quantity largely exceeding the theory.

. From this solution precipitates free diphenyldihydrazine, describedfor the first time by Arheidt. It is sucked of! on a funnel and washed,25 first with water, then with alcohol, and, finally, with ether. Theproduct is dried in desiccator in vacuo over sulfuric acid andparafiine. During the drying its color noticeably changes to a darkershade. The yield is about 5565 grams. 30 When heated in a capillary, thesubstance melts and decomposes at about 168-170 0. According to Arheidtit melts and decomposes at about -167 C.

(11). Preparation of di-methulpyrazolonyldiphenyl A thoroughlyhomogenized mixture of 35 grams of diphenyldihydrazine with 42.5 gramsof ethylacetoacetate is heated with reflux condenser 40 on a boilingwater bath for 6 hours. During that time the reaction mixture becomessolidified into a very dense amorphous mass of a very dark reddish-browncolor. It is heated with 1 liter of 4% sodium hydroxide on a boilingwater bath. 45 The resulting solution is filtered, and the filtrate ismixed with 1 liter of water and 100 cc. of glacial acetic acid. For amore rapid precipitation of the product, powdered sodium chloride isadded to the mixture. The mixture is left standand to the resultantsolution, after 20 filtered, thoroughly washed with water, and dried ina desiccator over sulfuric acid. The product represents amorphous powderof a light browncolor resembling the color of cocoa. The yield is about35 grams, or about by weight of the diphenyldihydrazine used. Whenheated in a capillary, the substance decomposes at about -143" 0.,rising and developing gas.

Being of the amphoteric type, the substance dissolves in alkalis as wellas in relatively strong acids. When diluted with a large amount ofwater, acid solutions of this di-pyrazolonyl precipitate amorphousflocculi of the free base, of a very pale cream color. The precipitationof the substance is expedited by the addition of powdered sodiumchloride to the mixture, although the largest part of the substancestill remains in solution. It finally precipitates after adding sodiumacetate to the solution.

The product, di-methylpyrazolonyl-diphenyl,

is represented by the formula? Bio-To TO-CH: 007 mo- N N= -omDi-methylpyrazolonyl-diphenyl easily couples under normal conditionswith diazotized aromatic amines, forming every time a correspondingbis-azo-compound. In particular, upon treatment with diazotized aniline,a corresponding bis-phenyl-azo-compound is formed, as per formula:

This azo-dye (di-phenylazo-di-methylpyrazolonyl-diphenyl) in a freestate represents a dark-red, almost black, usually amorphous substance,which very easily dissolves in solid acetone. It is practicallyinsoluble in water, 10% sodium hydroxide, and 10% hydrochloric acid.

When treating the hydrochloric acid suspension ofdi-methylpyrazolonyl-diphenyl with nitrous acid (HNOz), a correspondingdi-nitroso compound is formed, as per formula:

8,011,256 ing for 12 hours, then the settled precipitate is 'however,very promptly precipitate amorphous dark-red flocculi.

The di-nitroso-compound is practically insoluble in water, ether. andbenzene, but is easily soluble in glacial acetic acid, cold acetone,absolute alcohol, and chloroform. The solution of this substance inacetone, glacial acetic acid, and alcohol, ispre'clpitated by water inthe form of amorphous, pale light-brown, or orange, flocculi.

The dark colored solutions of di-nitroso compounds in acetic acid areeasily reduced by zinc dust, changing their color to light pale yellow,or becoming almost colorless. Nothing is precipitated upon dilution withwater, but when left standing for a long time, the solutions regain thered color and begin to precipitate small amorphous flocculi of a darkred-brown color.

The reduction by zinc dust leads to the formation of a correspondingdi-amido-dipyrazolonyl.

The analysis of its hydrochloride fully corresponds to the followingformula:

These diamido-compounds (diamido-di-methylpyrazolonyl-diphenyl) becomeevidently oxidized when left standing, turning in all probability intocorresponding analogs of rubazonic acid.

I claim as my invention:

1. Method of producing di-methylpyrazolonyldiphenyl, consisting inheating a mixture of diphenyldihydrazine with ethylacetoacetate.

2. A method of producing di-methylpyrazolonyl-diphenyl, consisting inheating a mixture of diphenyldihydrazine with ethylacetoacetate, addingsodium hydroxide to the resultant mass and heating the mixture, andprecipitating the product by an acid.

IWAN I. OS'I'ROMISLENSKY.

